


Principia Discordia

by aprettysmalldose



Category: Teen Wolf (TV)
Genre: Canon Compliant, Dubious Consent, Frottage, M/M, Masturbation, Mind fuckery, Underage Sex, Voyeurism, dark!fic, dark!stiles, possessed!stiles, post s03e17, season 3b spoilers
Language: English
Status: In-Progress
Published: 2014-02-05
Updated: 2014-02-05
Packaged: 2018-01-11 06:16:27
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,227
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1169674
Author URL: https://archiveofourown.org/users/aprettysmalldose/pseuds/aprettysmalldose
Summary: <blockquote class="userstuff">
              <p>The first time Derek sees Stiles after he returns to Beacon Hills, he immediately sense something is wrong. Stiles is possessed, but by what? And if Derek is the only one who notices, then is Derek losing his mind?</p>
            </blockquote>





	Principia Discordia

**Author's Note:**

> see notes at end for detailed warnings
> 
> summary and beta provided by my beloved Josh :) [broodingsoul](http://broodingsoul.tumblr.com/)
> 
> inspired by these posts [here](http://onelastwaltz.tumblr.com/post/75607505943/reliand-zainclaw-ok-but-guys-picture-it-for) and [here](http://twerkbrien.tumblr.com/post/75557416262/im-going-to-need-fic-stat-where-derek-finally)

Chapter I

~~~

Be near me 

 

 

It occurs to Derek, just before he looks over to Stiles, that he _hasn’t_ seen Stiles since he’s been back. Which is odd, because previously he hadn't been able to _breathe_ in Beacon Hills without tripping over Stiles.

 

Something relaxes in Derek's chest as he glances over to Stiles; some unrealized tension laid to rest as Derek lets his eyes drift over Stiles' body as he freaks out (in typical Stiles fashion) over the previous night's events in the McCall residence.

 

"Japanese demons now," Stiles groans, and Derek lets his eyes roam over the McCall living room, looking a little worse for the wear, but still functional.

 

The phrase, 'everything the same' floats to his mind for some reason. He exchanges a cautious nod with Allison, a deeper look with Isaac, and he checks on the Kitsune girl's aura again, almost out of habit.

 

"And when did _you_ get back?" Stiles is rounding on him, and Derek doesn't fight the smirk that rises to his face, languidly letting his werewolf enhanced vision slip off as he turns to face him, vague thoughts of poking at Stiles like a porcupine or badger; some irritable woodland creature. For whatever reason, it never fails to make Derek feel better about his situation, whatever that situation may be.

 

And then he freezes, smirk falling from his lips as he catches the edges of it, presses in his mind to bring back the full extent of his vision to catch the aura of warped darkness curling around Stiles, even as it fades -- almost as if it's being sucked back inside his skin.

 

"Stiles," Derek says, "What's wrong?"

 

Stiles blinks at him in confusion, "What, you mean, like right now? Except at being pissed at your non-communicative werewolf ass, nothing."

 

Except that's a lie. Scott's face creases up in confusion and he half-turns to Stiles, looks like he caught it too.

 

But Scott doesn't press it, and Derek does. "Tell me," he demands.

 

Stiles throws his hands up in the air, "Other than the fabulous events occurring the past few nights? _Nothing_ , Derek, or are strange new demons and the murder twins not enough for you?"

 

Recognizing Stiles' deflection for what it is doesn't stop Derek's head from turning towards the pair standing in the far corner reflexively. He glares at them, and they shift uncomfortably, almost as one.

 

 _Not a killer,_ he reminds himself, _not a killer._

 

He turns back to Stiles, frown making his eyebrows draw down and heavy on his face. Stiles stares right back at him, makes a face - just - one of those faces that Stiles makes, familiar to anyone who's spent any kind of time with him, and Derek is overcome by the certainty that the boy standing in front of him is _not_ Stiles.

 

He inhales deeply, puts everything he has into it, goes almost full beta-shift, the halo of his enhanced vision falling over his eyes, his finely tuned ears tracking the sound of the blood in Stiles' veins.

 

He smells like Stiles, he _looks_ like Stiles, no further trace of darkness in or around his skin. But the blood through his veins, the cadence of his heartbeat, it's...off somehow, in a way Derek knows he won't be able to explain. Though the rhythm of Stiles' heart is right, it sounds like it's coming through on a different frequency, slight, like something is filtering the sound before it can reach Derek's ears.

 

"Dude, what is it," Scott is saying, alarmed, as he turns around, the alpha red bleeding into his eyes as he searches for the threat he thinks Derek sees.

 

Derek relaxes, releases his hold on the shift and snaps his eyes back to Stiles', who looks done, ready to throw all werewolves ever off a bridge. And that's right, that's Stiles, that's what he does, but the hair on the back of Derek's neck is standing on end, the muscles of his back are coiled and tense. _Threat,_ his body is telling him, and every instinct that he possesses is screaming it.

 

"Who are you?" He says calmly, to Stiles, or what looks like Stiles, sounds like Stiles, smells like Stiles and _almost_ feels like Stiles.

 

"Huh?" Scott asks.

 

"Derek," says Stiles dramatically, "I am your father."

 

"Ugh," groans Isaac, "will you two cut it out already? Allison and I need to tell you about the nogitsune."

 

"Scott," Derek says as he turns to him, "Scott, that's not Stiles."

 

Scott blinks at him, uncomprehending, looking baffled in a way he hasn't for a while. "What are you talking about?" he says, wrinkling his nose in confusion. "Of course that's Stiles."

 

"There's something wrong with him," Derek says, doing his best not to clench his teeth or growl. Scott has to be handled carefully, or he'll go right back to hating Derek, and Derek really did not enjoy the portion of his life that that time entailed.  

 

"There's something wrong with your _face_ ," Stiles snarks.

 

Allison smirks, and Derek hears the twins shuffle their feet, off to the side in their little corner.

 

Derek closes his eyes, takes a calming breath. He's not going to get anywhere right now, with this crowd here. He's going to have to talk to Scott  later, when he can get him on his own.

 

"Fine," he grunts, dropping it.

 

Allison explains about her father's encounter, 24 years ago, and as everyone turns towards her, giving her their attention, Derek keeps his eyes on Stiles.

 

No one else sees it, it's meant for him alone, when the corner of Stiles' mouth tips up into an unfamiliar smirk, (Stiles has 10,000 smirks, and this is not one of them), and he gives a condescending wink to Derek.

 

Derek's heart sinks like a stone in his chest. _Wrong, wrong, wrong_ the cells of his body chant.   _Not Stiles,_ scream his instincts; the gifts of his blood.

 

 

 

 *****

 

Talking with Scott does not go well. "Of course he's Stiles," Scott says, annoyed, leaning against the door frame just inside his bedroom.

 

"No Scott," Derek tries again patiently, "He's not he's..." Derek struggles for a moment for the words that won't come. "Wrong," he finishes lamely.

 

"He's having problems with the, um..." Scott pauses for a moment, having his own problem with words. "The...ice bath mojo jojo, but so are Allison and I, and all three of us are doing better."

 

Derek tries to explain about the darkness in and around Stiles, but Scott just scrunches up his nose again (belligerently, this time) and says, "I've seen Kira's aura, but I've never seen anything around Stiles."

 

"But _I've_ seen it," Derek tries to patiently explain.

 

Scott just railroads over him with, " _besides_ , even if there was, it's probably something to do with the whole 'sacrificed ourselves' thing."

 

Derek doesn't push Scott any farther. Scott doesn't sense anything wrong, and explaining to him why Derek knows so much about Stiles and how his body runs probably isn't the best idea.

 

He's not going to go there. Ever.

 

 

 

 

 

 *****

 

 

That night, Derek lies on top of his sheets, one arm crossed behind his head, the other resting on his bare stomach, comfortable in his soft cotton sleeper pants (a gift from Cora) and tries (unsuccessfully) to convince himself that Scott is right.

 

Stiles is Stiles and there's nothing wrong, other than the obvious.

 

It doesn't work.

 

He has a dream that Stiles is behind him, his long fingers stroking down Derek's chest, his voice whispering things in Derek's ear. Derek doesn't remember them when he wakes, but he knows they were obscene. His whole body aches with need when he wakes. His noble intentions only last a few minutes before he gives in and jerks off to the phantom memory of Stiles' breath at his ear.

 

 

 

 

 

 *****

 

 

The next few days are a special sort of hell, one that Derek feels he's sliding into, one inch of sanity at a time.

 

"The way blood on your hands slicks up your fingers, it's fabulous don't you think?" Derek _swears_ Stiles whispers next to him, and even though all of the other werewolves should have been able to hear it, no one bats an eye.

 

They're gathered in the Stilinski kitchen, listening to the Sheriff describe a new, incredibly gruesome crime scene with weariness and regret coloring his tone.

 

The victim is a boy called Greenberg.

 

"Poor Coach," Stiles whispers, and this time everyone hears him, his face crumpling as hefights back tears.

 

Derek doesn’t know what to do. Is he losing his mind? Is Stiles? Is there a darkness at their door, or is it all shadows and smoke; figures just out of sight?

 

They all look defeated that night.

 

 

 

 *****

 

“Tell me you want me,” Stiles says over the phone, voice low and husky and _sex._

 

“Wha-?” Derek says, the material of his cell phone giving a strained groan as his hand clenches down around it.

 

“I _said_ ,” Stiles says exaggeratedly, “my dad got a new deputy. Scott’s off chasing a lead at Deaton’s, can _you, oh mighty sourwolf,_ go sniff him out for me, make sure he’s not gonna try and snack on the Sheriff?”

 

“Yeah,” Derek says, wrong footed, feeling that events are spiraling out of his control, out of his sphere of reference. “Sure.”  

 

 

 

 

 

 *****

 

 

Another day, another fight resulting in Derek knocked flat on his back to the ground. Kitsune, Oni, and now Youma. Derek used to want to see the world, but not anymore. Other countries can keep their exotic merchandise for themselves, Derek has had more than his fill in Beacon Hills.

 

Stiles extends a hand to Derek, hauls him to his feet with ease. Derek had let himself be dead weight, had wanted Stiles to have a hard time with it, bitch him out for it. He feels the stare he’s giving Stiles turn almost wild, desperate.

 

“Up and at ‘em big guy,” Stiles says, clapping him on the shoulder, “ _So much more failing to do, so little time to do it,”_  he finishes, open, almost bright expression on his face never changing, but his voice turns mocking and cold. His words fall deep, likes stones, in the well of shame in Derek, the well that never runs dry; the well that’s never closed over.

 

 

 

 

 

 *****

 

 

There are touches. Along his arm, on his back, and they look so innocent. Because touching each other like that, a quick gesture of support and companionship, that was them, a thing they did, a point their relationship had gotten to, before Derek left and came back to find something else in Stiles’ place. Touches that no one raises an eyebrow at, or probably even consciously notices.

 

They make his skin crawl at the same time they ignite the blood that runs underneath. Touches that remind him of guilt and want; ash and desire and self-loathing, all swirling together, pent up in his gut. They’re familiar, not just because it’s Stiles and Derek long ago memorized his fingers (another battle lost against himself), but because Derek has been touched like that before.

 

Touches that on the surface look to be without motive; touches that make him stumble. Touches that make him starve. Touches that leave only mourning and longing in their wake.

 

 

 

 

 

 *****

 

 

Stiles presses himself up against Derek’s back one night, when Derek’s let down his guard, forgetting somehow about the wrongness that is consuming Stiles, a wrongness that Derek is powerless to halt. Stiles had offered Derek a ride, and he’d accepted, simple and clean. The others have left, the lot empty; the air stilted. The space is vacant and not very forthcoming, just like the answers they don’t have.

 

“I know you want this,” Stiles’ breath ghosts over the shell of his ear. They’re of a height now. Soon Stiles will join Isaac in towering over them all. “Want _him,_ don’t you?” ( _Not Stiles, Not-Stiles)_ Stiles taunts, long and lean -- the length of him an unpardonable sin pressed up against Derek’s body.

 

Derek shudders as the whispering continues, his body made vulnerable and lost by his own twisted desires.

 

“You want to..” there’s just the slightest hesitation as the voice draws out the next word like a delicacy, “ _fuck_ him, swallow down all his cries with your mouth.”

 

“No,” Derek whimpers, small and unresisting.

 

He can feel the smile on the lips as they move yet closer to Derek’s ear. “Draw his blood with your teeth, mark and take and own and break.”

 

Derek presses his front even closer to the passenger door of Stiles’ ridiculous jeep, but Stiles’ body just follows him, his scent engulfing Derek, his fingers tracing down Derek’s spine through his grey sweater.

 

“You can, you know. You can have him. He wants you.”

 

“Stop,” Derek grits out, his breathing ragged, his voice harsh. Derek knows if he turns, he’ll see Stiles in that face, maybe laughing or annoyed, living this moment on some other plane, carrying on the conversation he most likely _thinks_ he’s having with Derek. He doesn’t turn.

 

Stiles (is it Stiles? sometimes it is Derek can never be sure, never be sure…) chuckles and continues, and what he says makes Derek press back against him, lean into him despite his intentions; despite the ‘not Stiles, not-Stiles’ he’s chanting in his mind.

 

“Or maybe I should let him have you? Ohh, he would love that, so much, we both would, press these fingers into you,” and his fingers come up to stroke the backs of his knuckles gently against the side of Derek’s neck, “make you beg and cry as you come, he thinks that you have beautiful tears, his memories are that you’re beautiful when you cry.”

 

“Stop,” Derek says again, but it’s more of a sob, a sob for so many reasons. Because his knees are weak and his face is flushed. Because his stomach aches, and his teeth and nails itch, longing to be free, so Derek can turn, rip tear kill.

 

A hand slides around Derek’s waist, dips down to rub against his crotch. He’s hard.

 

“Yes I think so,” Stiles says, voice light, amusement coloring his tone, a world away though he’s right next to Derek “ _But not tonight,_ ” the other voice finishes and the hand withdraws. Stiles steps away and walks around the front of the jeep to the driver’s side. Derek opens his door, numb, shamed, and wanting so fiercely he’s sick with it, in all meanings of the word.

 

He wants to die, he wants to fall back on the concrete, arch his back and bare his neck. As he climbs up in the jeep, he wants to reach over and plunge his claws into Stiles’ skin, until the passenger riding him is drawn out, trickling in his blood onto the floor, he wants to reach over and shove his hands downs Stiles’ pants, work him over until he screams in ecstasy.

 

As Stiles drives him to his loft, Derek knows, feeling faint, that all of these things are equally possible.

 

 

 

 

 

 *****

 

 

Two mornings later, Derek slides open the loft door to reveal Stiles, jittering from side to side as he waits.

 

“Derek,” he gasps, and half falls down the steps in his haste to make it down into the loft.

 

“Stiles, what?” Derek asks eloquently before Stiles turns to him, holding up a pendant from where it’s dangling around his neck.

 

“I talked to Deaton about how confused I’ve been, and he gave me this, this amulet thing to keep out whatever it is that’s running around inside me! It’s only temporary, but it’s better than nothing.”

 

Derek feels less the weight of 2 tons, and takes two staggering steps forward to wrap his arms around Stiles.

 

“Good,” he whispers fiercely chokes on a brittle laugh, “thank fuck.” He gets a hold of himself after a moment, starts guiltily, and pulls back, but Stiles’ hands come up to frame his face, and Derek’s heart lurches. He’s overcome with the desire to - just - kneel down before Stiles and give and give and give.

 

 _Fuck,_ he thinks in that moment, _I love him, this kid, this boy, this man._

 

He’s not sure if that makes things better, or worse.

 

“Derek,” Stiles says seriously, tilting Derek’s head until they’re staring into each other’s eyes, “I want you to know that this is me. Right now? This is me.”

 

Derek opens his mouth, likely to ask some sort of inane question or another but he never gets a chance, because Stiles crosses that distance between them to gently press his lips against Derek’s.

 

Derek feels it, that sweet kiss, feels it down in his bones, in his veins, capillaries, nerves; a connection between them, a moment where everything else in the world ceases to exist.

 

His eyes flutter closed, and he presses back, softly, cautiously.  

 

Stiles pulls away, then presses forward again, placing kiss after delicate kiss against Derek’s mouth. “Derek, Derek, Derek,” he murmurs in between each of them, sounding plaintive and hopeful.  

 

Derek catches at Stiles’ mouth with his lips when Stiles leans back in again after another pull back, and then it’s just one kiss, one burning kiss where their mouths press against each other, pull against each other, find new and better ways to fit together.

 

“Kiss me kiss me kiss me,” Stiles gasps into Derek’s mouth, and then before Derek can stop himself, his tongue is sliding inside Stiles’ mouth, tasting the vibrations as he moans. Their tongues tangle and slide against each other; Derek swiping through in long strokes, Stiles’ darting into Derek’s for quick teasing tastes.

 

Derek can’t stop, won’t stop as they stagger over to the large table at the window, pulling at each other’s shirts as they do their best not to let their mouths separate.  

 

Once Derek has Stiles’ shirt off, his hands slide down his sides, across his chest and up his back, eager to take, eager to have the touching of that smooth, pale skin for his own.

 

Derek feels Stiles’ hand slip under the waist of his jeans, inside his under armour, groans deep from his chest at the feeling of Stiles’ fingers clenching on the muscle of his ass.

 

Their hips are rocking into each other and Derek feels the answering hardness of Stiles’ cock where it presses against his own. He pants, chest heaving with short gasps as he presses Stiles onto the table, chest to chest and groin to groin. Stiles throws back his head as Derek kisses down his neck, works his skin with lips and tongue and teeth, the taste of him, the smell of him, everything Derek’s ever wanted. Everything he should never have, and takes anyway.

 

“Gonna--gonna come,” Stiles gasps as Derek ruts down into him, the friction of his jeans against Stiles’ similarly clad cock both a blessing and a curse. He kisses down Stiles’ chest, swirls his tongue around  the tightened nub of a nipple.

 

“Oh god,” Stiles pants, “Oh god, fuck me _fuck me_ stick your cock in me and split me open with it.”

 

A hot spike of arousal lances through Derek’s body at the same time that the heavy weight of dread slams back down on his shoulders, and his body freezes on Stiles’.

 

“Stiles?” Derek asks. He doesn’t know why, he already knows the answer. He slowly lifts his head up, eyes unable to see the expression on Stiles’ face from this angle, he’s got his head tipped so far back.

 

“I just can’t handle all these sweet _feelings_ ,” his voice complains, and this close Derek can feel the vibrations in his chest, can feel the wrong. “Just flip me over, take your big werewolf cock, and pound into me already.”

 

Derek flings himself off of Stiles, who heaves a disgusted sigh and pushes himself up on one elbow, splaying his legs and arching his back like a whore, wanton and deliberate.  “Gotcha,” he laughs, and tosses the pendant off from around his neck. “Aw,” he fake pouts at Derek, “guess we’re all done playing for the day?”

 

Derek takes a deliberate step back.

 

Stiles snaps open the button on his pants and drags his zipper down. “I wanted to come,” he whines, and licks a broad strip with his tongue over the palm of his free hand. “He wants it all the time, and who are we to deny him?” Stiles ( _not Stiles)_ taunts.

 

Derek can’t stop from inhaling the scent of Stiles’ arousal as it intensifies throughout the loft.

 

“Mmm,” Stiles moans as he shoves his hand inside his blue briefs, and wraps it around his cock. His eyes meet Derek’s; challenging, ardent and mocking. Derek can’t look away, doesn’t want to. _It’s not Stiles, it’s not Stiles,_ he thinks, over and over again, but his body doesn’t believe him. His cock and balls ache within the confine of his jeans, and every fiber of Derek, every cell of his body _wants._

 

“He’s in here,” Stiles whispers, the calmness of his voice at odds with the thrashing of his body as he falls back on the table and yanks his underwear down, exposing his cock, leaking around the fist he has on it, thrusting his hips up into his grip.  “He wants you, oh how he wants you, even as he never wants to see you again after this little interlude.”

 

Derek’s hands clench into fists at his side.

 

“But don’t worry, we’ll come back some night,” the voice laughs as Stiles jerks and writhes and drives Derek’s body insane with lust, “come back and fuck you and make you fuck, and you’ll want it, and so will he, and I’ll let you have it, but you’ll be so tainted, so tainted and _mine,_ ” and on the last word, Stiles arches up and his body goes rigid as he comes, the arm he’s using to continue to jerk his cock the only movement as he coats his chest and fingers with the long white stripes of his seed.

 

The smell of it, the sight of it; Derek knows what Stiles looks like in the throes of orgasm now, he’ll never be able to unsee or forget it. It will haunt him at night and in his dreams, he’ll never be able to stop reaching for it everytime he reaches to touch himself.

 

“Mmph,” Stiles groans as he slides off the table, licking his fingers clean. Derek feels his fangs fight to descend at the sight of it. Stiles strolls up to Derek, a sensual roll to his hips that has Derek closing his eyes against the pure want roiling through his body. Stiles stops right in front of Derek and looks at him earnestly.

 

“It’s really only just the beginning,”  Stiles says with a contented smile and the air of one imparting a tidbit of wisdom.  He traces a finger through the mess on his chest, provocative and obscene. Derek’s breath catches in his chest. His mouth parts open on reflex to take in a breath and Stiles reaches out and gently slides his finger along the swell of Derek’s bottom lip, leaving the trail of his cum behind.

 

Derek doesn’t believe in a god, but if he did, he would ask for god to help him, because he hasn’t the strength to keep his tongue from slipping out and licking over his bottom lip, the taste of Stiles all the levels of bitterness that the word possesses.  

 

And then, Not-Stiles is gone and Derek is looking straight at Stiles, the real Stiles, and Stiles is staring back at him. Stiles is seeing him and he’s there and real, probably for the first time in weeks, maybe even since before Derek got back.

 

There’s a moment where they stare at each other, and Derek knows the agony is reflected in both their eyes, and then Stiles is screaming, wailing, in horror and hurt, beating at Derek with his fists, and all Derek can do is let him; wrap Stiles in a hold to stop him from clawing at his own face.

 

“God Derek, make it stop, get it out of me!”

 

“I will I will,” Derek promises, fighting against the heat in his eyes and the tightness in his throat. He doesn’t know how, he’s so lost, he doesn’t know what to do or how to do it, “I won’t rest until you’re rid of it.”

 

 

 

 

 

 

 *****

 

 

“Don’t trust me,” Stiles says before he leaves, a defeated tone in his voice, “Don’t let me be alone with Scott.”

 

Derek can’t find anything to say, and then he’s alone again, the weight of inadequacy heavy enough that it feels as if he’s being dragged to the floor. But he’s not beaten. Not yet.

 

“Not yet, Stiles,” he whispers. “Not yet.”  And he turns to his library of Arcana, prepping to go and see Deaton in the morning, wondering if it’s possible to track down Deucalion. Wondering if Gerard is still alive.

 

The only one he won’t turn to is Peter, because he knows, deep inside that Peter can’t be trusted around a Stiles who isn’t himself, even more than Derek can’t be.

 

He’ll crawl on his knees and beg for knowledge of how to free Stiles at the feet of his foes if he has to.

 

 _Fall down 7 times,_ his father’s voice echoes warmly in his memories, _get up 8._

  
  
  
  
  
  
  
  


**Author's Note:**

> Stiles is possessed by a dark something, and most of the events he is blacked out for, or perceives as happening differently. At the end, he is fully aware of everything that transpires in Derek's loft, but is in control for none of it. He is attracted to Derek, wants to have sex with Derek, and even has some unrealized feelings. He is underage and un-consenting, though at the time, Derek is only aware of the underage portion of it. 
> 
> I have tagged for warnings, but I don't become triggered by reading things, so if there's a warning I'm missing or a better summary of all the stuff going on here at the end needed, pls let me know :)
> 
> THIS FAN FICTION BROUGHT TO YOU BY MY OBSESSION WITH STEREK, POWERED BY [TUMBLR](http://rizuno.tumblr.com/).


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